Corrosion-resisting flexible connector



Jan. 19, 1954 J. G. HOWARD ET AL 2,666,657

CORROSION-RESISTING FLEXIBLE CONNECTOR Filed Feb. 17, 1950 /0 I9 I ,5 iZ M 8 JYZVE 77%575 U'a/m 6'. Howard Pa mohd /7. Thomas 27 ,7 J5 H/f zPatented Jan. 19, 1954 CORROSION-RESISTING FLEXIBLE CONNECTOR John. G.Howard and Raymond Harry Thomas, Chicago, Ill., assignors to ThePyle-National 7 Company, Chicago, 111., a'corporation of New Jersey-Application February 17, 1950, Serial No. 144,714

This invention relates generally to a flexible electrical connector asis frequently employed between an electrical conduit and an operating 3Claims. (01. 285-206) mechanism, or between two electrical conduits Vwhich must be placed in communication with one another.

More specifically, the present invention relates to a novelcorrosion-resisting flexible connector and a process for making such astructure, all of the elements employed in the structure being made ofsuch a material as to effectively resist the deleterious effect ofexposure to an environment in which harmful or dangerous corrosionoccurs.

Flexible fittings have been provided heretofore whichwere particularlydesigned to fulfill the safety requirements attendant upon the use ofsuch fittings in a hazardous location, for example, a location where anexplosive mixture is likely to prevail in the atmosphere surroundingtheeleotrical fittings. Such fittings have usually been made out ofordinary metals which are not corrosion-resistant and have beenfabricated in a conventional manner by use of ordinary welding orbrazing or soldering procedures.

A fitting of this nature, of course, is seriously deficient if itisnecessary to employ the flexible electrical fitting in an environmentwhere not,

only are explosive mixtures likely to be present,

but the atmosphere surrounding the fittings is metal coupling connectoris placed in abutting relationship thereto. All of these elements aremade of a suitable corrosion-resistant metal such as stainless steel orthe like. An electric-arc welding process is then employed to integrateall of the aforementioned elements. The welded joints are also resistantto attack by corrosive substances. The inner bore of the bellows-liketube is then lined with a tubular loom of flexible electricallynon-conductive material and the loom is locked against axialdisplacement to complete the assembly of the fitting.

It is, therefore, an object of the present invention to provide acorrosion-resistant electrical connection fitting which overcomes thedeficiencies of flexible fittings heretofore provided.

Another object of the present inventionis to provide a process formaking a corrosion-resistant flexible electrical connection fitting bywhich the fitting may be suitably lined with a flexible electricallynon-conductive material, but during the assembly of which, the linedmaterial will not be consumed or damaged because of exposure toexcessive temperatures.

A further object of the present invention is to provide a flexibleelectrical connection fitting which will not only offer protectionagainst explosion hazards, but will, in addition, resist attack bycorrosive substances surrounding the fltting.

Another object of the present invention is to g Figure '1 is anelevational view of an explosion proof, corrosion-resistant electricalconnection fitting according to the present invention;

Figure 2 is a slightly enlarged cross-sectional view, broken in part, ofthe fitting shown in Figure 1;

Figure 3 is an enlarged cross-sectional exploded view showing additionaldetails of construction and helping to explain the steps of the processof the present invention; and

Figure 4 is a fragmentary cross-sectional view 6 of an alternativeembodiment of the present invention.

As shown on the drawings:

In providing a flexible electrical connection fitting, it is necessaryto employ a body portion which is flexible to a marked degree and whichwill be expansible without damage in the event the body is exposed tothe shock of an explosion. The body must also eifect a flame-proof sealof the conductors enclosed thereby to preclude inadvertent ignition ofexplosive mixtures surrounding the fitting.

It will be readily apparent, however, that v the body must also be sosubstantial and so strong that should an arcing occur within the body ofthe fitting, there must be no danger of burning through the body wall.

In meeting these difiiculties, flexible fittings joints provided byelectric welding,' gas"wlditig;

brazing, or soldering are all susceptible to as struction when subjectedto the attack oi con:

rosive substances. Thus, even if" sub him on of materials were made sothat thefleiible braided sleeve and the bellows-like tube were made ofcorrosive-resistant material, the fitting would be deficient because thejoints-would hesubject' to deterioration and hence, the fitting wouldnot fulfill the safety requirements necessary for employment in ahazardous location. 7 H t Onthe cther'hand, if special techniques areemployed in producing a corrosion-resistant joint, for example, thetechnique of stainless steel welding, the heat produced during thecourse of the welding procedure is so excessive as toconsume orseriously damage the tubular loom.

may be employed to integrate the coupling connectors l6 and [1, therings 13 and M, the bellows-like tube II and the flexible braided sleevel2, thereby producing a pair of welded joints indicated generally by thereference numeral l9, |9[(Fig. 2),. Y

After all of the aforementioned elements have been placed in firmassembly with one another by 'wlding, the inside bore of thebellows-like tube "10 made of an electrically non-conductive material I[is "liiie dw-ith a flexible tubular loom preferably ir di c atedgenerally loy'the reference numeral 20. r the loom has been positionedwithin tileinting, it-isdolred against axial displacement. As showni'nthe embodiment of Figures 2 an d, 3, thefemale coupling connector i6is provided with an annular ring-seating groove drawings, the presentinvention contemplates the provision of an explosion-proofcorrosionresistant flexible electrical connection fitting which isindicated generally by the reference numeral H]. A bellows like' tube'llmade of a corrosion-resistant metal such as stainless steel or" the likeis provided'and a flexible metal braid ed sleeve I2, also made of acorrosion-resistant metalsu'ch as stainless steel or the like,is placed.

in surrounding relationship to the tube: ll.

At each end of this sub-assembly and in concentric relationship theretois placed arnetal end fitting'prefera'bl'y made of a corrosion-resistantmetal such as stainless steel or the like. Asshow'n in this particularembodiment, the endfittings include a ring I3 and a ring" M;

A metal coupling connector made of a cor; rosion re'sista'nt metal suchas stainless steel is then placed in abutting relationship to thepreviously'assembled elements. As shown in this particular embodiment, afemale coupling conable for reception in a male coupling ,corir ectorl8"having 'a counterbore portion lilo and a-- smooth bore I 8b with anexternally threaded portion Ito. The ring l'l definesfa smooth bore Ilawith an annular ring-seating groove llb formed adjacent one end thereof.

It'may be noted that the bore 16?) of t'he fema e coupling connector andthe bore l'ia of-the ring I? are' approximately equal iii-diameter tothe diameter of the innermostundulations defined bythebell'ovvs-liketube H.

An'el'ectric-arcweldi'rig procs's,-preferably according to astainless-steel'welding technique;

=16c-and"'a pair of resilient snap rings 2|, 2|

are seated in the seating groove l6c of the female coupling connectorlS;- as well as" in the seating groove ill) of the ring H in substantialabutting relationship to the ends ofthe loom 29, thereby precludingaxial displacement of the loom 20 relative to the other elements of thefitting 10.

In the alternative embodiment of Figure 4, no intermediate elementcorresponding to the ring I l is provided and a male coupling connector22 having a smooth bore 22a-and an externally threaded portion 22biyintegrateddirectly with a bellows-like tube ll, a flexible braidedsleeve l2 and a ring 24' by means of a'welded joint I8. After the tube His lined with a." loo'm"'2ll', the loom 20' is locked in axialdisplacement by press fitting a bushing23 into thebore2 2a' ofithemale 7ing 23 and the bore 22a of the male coupling connector 22 can bedimensionally related so'that the bushing 23 may beplaced'in'firm'assembly'within themale coupling connector 22 with ashrink fit.

It may also be noted'that the'ring' ll and'the male coupling connectorl8' shown in the embodiment ofFiguresl, 2 and 3 may beint'egrated' withone another by-press fitting or shrink fitting as desired.

It will be evident "that the process of *rnaking a flexible fitting asdescribed completely eliminates the necessity of exposing the looms'2l'or Zil'to the excessive temperatures developed during avvelding process.Moreover, it will be evident that'all of the elements embodied in thefitting of this invention which are exposed to atmospheric conditionsincluding the welded joints is and I9f,-are made of corrosion-resistantmetal and are, therefore, capable of withstanding attack by corrosivesubstances. Thus, we have described a fitting which will successfullyoperateina corrosive atmosphere without danger of decreasing theexplosion-proof characteristics thereof v It is contemplated thatvariouspersons skilled in the art might suggest minor modifications tothe preferredembodiment herein shown and described in detail'for thesalge of clarity, however,

it should be understood that we wish to embody duit comprising, inner;outer, and intermediate concentric sleeves consisting of a flexiblecorrosion resistant metal braided sleeve, a flexible tubular loom ofelectrically non-conductive, heat consumable material, and a flexiblebellows-like corrosion-resistant metal tube, respectively, a femalecoupling connector having a bore extending therethrough of largerdiameter than said loom but of smaller diameter than said tube, aprotective ring surrounding the end of said concentric sleeves adjacentsaid coupling connector, an annular welded joint of corrosion-resistantmetal integrating by high temperature thermal fusion said couplingconnector, said ring, said braided sleeve, and said tube, and a retainermember inserted in said bore of said coupling connector and in firmassembly therewith and being of smaller diameter than said loom, saidloom being inserted through said bore of said coupling connector onlyafter said welded joint is sufficiently cooled to preclude consumptionof said loom, and said retainer being inserted in said bore to retainsaid loom in said conduit.

2. A corrosion-resistant flexible electrical conduit as defined in claim1 wherein said retainer References Cited in the file of this patentUNITED STATES PATENTS Number Name Date 1,993,984 Wulle et a1 Mar. 12,1935 2,025,545 Muff Dec. 24, 1935 2,360,608 Kauffman Oct. 1'7, 19442,e49,356 Wikoff Sept. 14, 1948 2,451,438 Hartman Oct. 12, 19482,452,057 Kehoe Oct. 26, 1948 2,516,631 Jacobson July 25, 1950

